For someone who lives close to some of the world's most wanted men, Abu Mudrik Bin Fahir takes a suprisingly neighbourly attitude. A tribal sheikh in the eastern Yemeni province of Shabwah, his fiefdom is wedged amid the mountains that serve as the main base for al-Qaeda in the Arabian Peninsula, the group that claims to have masterminded last month's parcel bomb plot.

Yet despite the threat of Yemeni government raids, CIA drone attacks and now, possible raids by American special forces, he predicts few people in his area will betray the militants to the authorities.

"Al-Qaeda live side by side with the locals, and many of them have married into local families," said the bearded 48-year-old, gesturing to the mountains beyond his home village of Amkiin. "They are part of the community."

Welcome to what Yemeni officials call "The Triangle of Evil" - the three rugged provinces of Shabwah, Mareb and Jof that form the strongholds of al-Qaeda's new franchise in Yemen. It is in this vast region of arid desert and jagged, Arizona-style canyons that the hunt is now on for Anwar Al Awlaki, the so-called YouTube preacher, and other senior figures behind the parcel bombs discovered on planes in Britain and Dubai ten days ago. Not that Sheikh Fahir thinks they stand much chance of being found.

"The terrain here is more inaccessible and tougher than Tora Bora in Afghanistan," he said, referring to the remote mountain caves where Osama Bin Laden famously gave the US forces the slip in 2001. "The British Army, when they were in Aden, struggled in these mountainous regions, and so I tell you, the weak Yemeni Army will have no chance whatsoever."

As he spoke last week, US security officials told The Sunday Telegraph that a new effort was underway to flush out Awlaki, whose internet-based sermons are blamed for recruiting hundreds of Muslims to the the cause of violent jihad, including Roshonara Choudhry, the London student convicted last week of the attempted murder of the MP Stephen Timms.

In the skies above Sheikh Fahir's village, the wasp-like sound of CIA-controlled drones could be heard, and in the southern Yemeni town of Jaar, where al-Qaeda supporters openly preach in the flyblown market, Yemeni troops mounted a ground operation in which a senior militant was reported killed. On Saturday, a Yemeni judge ordered police to find Awlak "dead or alive" after convening a trial for his alleged role in a plot to kill a Frenchman at a Yemeni oil compound.

US naval ships in the pirate-infested Gulf of Aden were also on alert, after receiving intelligence that Awlaki, along with Ibrahim Hassan al-Asiri, the Saudi-born explosives thought to have crafted the parcel bombs, might try to flee by sea to neighbouring Somalia. American officials believe the pair could easily be given passage in an Arab dhow from the smuggling gangs that traffick drugs, arms and people across the 200-mile wide stretch of water. The fugitives would then be offered shelter from fellow jihadists withal Shebab, the Somali al-Qaeda affiliate with which AQAP has cultivated ties.

"The US naval presence in the area is equipped to stop any vessel that falls under suspicion," said one American security source. "It is likely that some vessels will be halted and searched."

However, even if such a search were to scoop up Awlaki, it would have only limited effect on AQAP's operational capabilities. While the Yemeni-born, US educated preacher is the best known face of the movement, security experts say he is little more than a mid-ranking figure overall. The "Triangle of Evil" is home to scores of other senior commanders, who not only control an estimated 400 loyal fighters, but enjoy the tacit support of the tribes among whom they have made their home.

Unlike in Iraq, where al-Qaeda suffered a backlash after terrorising people in the neighbourhoods that embraced it, in Yemen the movement has been careful not to alienate its hosts. Taliban-style beheadings and amputations are rare, and its main targets are the Yemeni military and the West rather than local civilians.

It buys tribal loyalty by paying generous tithes, and benefits from the region's idiosynchratic traditions of hospitality: tribes who will readily wage decade-long feuds with each other over minor slights may nonethless baulk at handing over a guest to outside authority.

"al-Qaeda is playing on a mixture of tribal and customary law," said Gregory Johnsen, a fellow of the American Institute for Yemeni Studies and author of a respected blog on Yemeni affairs. "The tribes in Yemen also have a history of using outside forces, such as socialist movements, as a wedge against the state. There have also been instances of Qaeda buying hospitality, although in general it is a very murky picture in terms of what is going on."

In an area where most people earn less than $2 a day, al-Qaeda's brand of radical Islam is often seen as a purer cause than Yemen's weak and corrupt central government. Rather than just issueing bloodcurdling calls for jihad, AQAP propaganda also articulates tribal grievances about unemployment and the lack of money that the area gets from Yemen's oil industry, which has pipes snaking across the desert floor. As Sultan Fareed, a sheikh from Awlaki's home village of al-Saeed, said in a recent newspaper interview: "Al-Qaeda haven't killed anyone here, so we don't have to hand them to the authorities."

More worryingly for the West, the Yemeni authorities themselves often take a similarly ambivalent line. In a region where menfolk carry AK47s like walking sticks, it has historically found it simpler to bribe troublesome tribes than tackle them militarily, leaving it ill-equipped to quell a determined foe like al-Qaeda.

Take, for example, last month's siege against the al-Qaeda stronghold of Hawta, a typically Yemeni town of towering houses built into a cliffside in central Shabwah. Government forces, who surrounded the area with tanks and artillery, trumpeted it as a major blow against terrorism, but that was not how it was seemed to Sheikh Fahir, whose village lies just a few valleys away.

"The siege of Hawta was ended by sheikhs who negotiated with al-Qaeda militants to peacefully leave the town," he said. "The government had very little to do with it, though they made out to be their success. Al-Qaeda have just relocated to camps in the mountains."

Unable to rely on the Yemeni government, some factions within the Washington security establishment are now pushing President Barack Obama to authorise a beefed-up role for US covert operations in the region. The CIA has already conducted a number of drone missile strikes against suspected AQAP members, including one last December that killed several militants in Wadi Rafadh, a valley in Shabwah province. But now they want to extend their remit to include boots-on-the-ground missions, a move that has sparked objections from the Pentagon, which say that experience in Iraq and Afghanistan has shown that secretive spy-run operations have a habit of getting out of hand. Unlike US military operations, CIA missions do not require the permission of the Yemeni government.

"The CIA is pushing hard for control of greater clandestine operations in Yemen, but the Pentagon right up to Defence Secretary Robert Gates is very reluctant to grant this," observed Dan Goure, a Pentagon consultant. "I expect this decision to rise to the President."

Meanwhile, another debate is raging within the Awalik tribe itself, which is one of the largest in the region, over whether to continue to shelter its most infamous son. While some sheikhs believe that continuing to harbour Anwar al Awlaki will now bring nothing but trouble, others fear reprisals from al-Qaeda should they give him up. Last month, the government gave sheikhs from the tribe money and guns to start hunting for militants in their territory in the Awalik mountain range in Shabwah, but despite the involvement of about 1,000 men, a two-day operation yielded not a single arrest.

Saeed Obeid, a Yemeni expert and author of several books on al-Qaeda, is not surprised. "In the media and according to statements by tribal leaders, the Awalik tribe are with the government," he said. "But in their Internet forums, when you investigate it further, they claim that they don't accept any external intervention, and that they will never surrender Awlaki."